Scientists think they have solved the enigma of the five million-year-old whale graveyard discovered in Chile beside the Pan-American Highway. The creatures, one of the most amazing fossil discoveries in recent years, may have perished in four mass strandings after swallowing toxic algae, according to a paper that was just published in the Royal Society Journal B.
The fossils are therefore believed to have been preserved as a result of the animal corpses being buried by sand over time after being swept into an estuary.
Following its discovery in 2010 during the Pan-American Highway’s extension project, the Atacama Desert in northern Chile has gained recognition for its ability to preserve whale fossils.
Many people gave the location the moniker Cerro Ballena, or “whale hill,” since they could see bones poking out of the granite walls there.
When a cutting was made to expand the roadway in 2011, American and Chilean paleontologists were finally given the chance to fully explore the fossil beds.
According to the BBC, experts from Chile and a team from the Smithsonian’s National Museum of Natural History had just two weeks to do their research before the large plant came back to finish building the new road.
The crew captured as much information as they could and built 3D reconstructions of the bone remains as they were found. Additionally, they took several bones from the scene for for laboratory research. The researchers discovered skeletons of billfish, seals, and aquatic sloths in addition to the more than 40 massive baleen whale skeletons that predominated the site. They also discovered the remnants of an extinct walrus-like whale and dolphins that had grown a walrus-like visage.” It amazes me that we were able to sample every celebrity of the fossil marine mammal world in South America during the Late Miocene with just 240 meters of road-cut.
Simply a very rich collection of species, “Paleontologist Nicholas Pyenson of the National Museum of Natural History at the Smithsonian told the BBC.
The group also took notice of how the corpses were set up. The largely full skeletons were preserved at four different layers, indicating a recurring and similar underlying cause of death. However, the various fossil layers revealed that it was really four distinct incidents spaced out over a number of thousand years, rather than one single event.
The researchers came to the conclusion that the animals were probably poisoned by toxins produced by toxic algal blooms. Death would have come quickly if the algae had been swallowed or if a significant amount of infected prey had been devoured.
Whether they were whales, seals, or billfish, all of the organisms we discovered ate at the top of the marine food chain, which would have rendered them extremely vulnerable to toxic algal blooms, according to Dr. Pyenson.
In the late Miocene, the remains would have been directed into a prohibited region by Cerro Ballena’s shoreline (five to 11-million-years-ago). The dying or dead animals would have been safe from sea scavengers while trapped on the tidal flat.
However, because no unique algal cell fragments were found in the sediments, the researchers was unable to conclude with certainty that toxic algal blooms were to blame for the mass strandings. They did discover many grains covered with iron oxides, which would indicate previous algal activity.
Added Dr. Pyenson: “The entire site is covered with mats that resemble algae. Although we are unable to confirm if these were the deadly algae, the sedimentology does not disprove the theory that toxic algal blooms were to blame for the incident.”